Guides
These guides answer the questions people actually arrive with: why a file did not shrink, which format to keep, what a setting really changes, and how a web page can process a file without sending it anywhere. Each one states where the technique stops working, because that is usually the part that decides what you should do next.
Image formats
Which format to keep, what a quality setting changes, and what metadata travels with a photograph.
- JPEG, PNG, WebP or AVIF: which should you keep?5 min read · reviewed August 17, 2026
- How to reduce image file size5 min read · reviewed August 28, 2026
- What is HEIC, and should you keep it or JPEG?4 min read · reviewed August 28, 2026
- What metadata is in your photos — and what removing it does not do4 min read · reviewed August 17, 2026
Where the bytes in a document actually live, and which compression mode a document can survive.
Video
Containers against codecs, and the settings that decide how large a clip ends up.
Local processing and privacy
How a browser can do this work at all, how to verify it, and where a device runs out of room.